Editor’s note: This article first appeared in the November/December 2000 edition of Grading & Excavation Contractor.
For this primer on metallurgy and welding, the author interviewed an expert in the arc-welding field, Thomas J. Black, manager of hardfacing and high-alloy products for The Lincoln Electric Company in Cleveland, OH. Black, a metallurgical engineer, has more than 40 years’ experience in the welding field.
What are the main kinds of steel used in the fabrication of construction equipment?
Black: Most of the components of construction equipment are made of some type of carbon steel. Carbon steel is the most widely used type of steel, used for fabricating structural steel for buildings, for automobiles, for washing machines, and so on. A carbon steel consists mainly of iron with some carbon—anywhere from 0.1 to 0.5%—and some silicon and manganese. There are no other alloying elements.
Editor's note: This article first appeared in the November/December 2000 edition of Grading & Excavation Contractor.
For this primer on metallurgy and welding, the author interviewed an expert in the arc-welding field, Thomas J. Black, manager of hardfacing and high-alloy products for The Lincoln Electric Company in Cleveland, OH. Black, a metallurgical engineer, has more than 40 years’ experience in the welding field.
What are the main kinds of steel used in the fabrication of construction equipment?
Black: Most of the components of construction equipment are made of some type of carbon steel. Carbon steel is the most widely used type of steel, used for fabricating structural steel for buildings, for automobiles, for washing machines, and so on. A carbon steel consists mainly of iron with some carbon—anywhere from 0.1 to 0.5%—and some silicon and manganese. There are no other alloying elements.
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If the carbon content of the carbon steel is low—0.1-0.35%—it is referred to as a mild steel or a mild carbon steel. Most construction equipment is made out of a carbon steel with a carbon content ranging from 0.1 to 0.25%, a tensile strength of 30,000-50,000 psi, and a Rockwell hardness of 5 Rc. To compare that with something more familiar, the steel used for the skeletal structure of buildings, A36 steel, is quite similar—carbon content, below 0.25%; tensile strength, 30,000-50,000 psi.
Besides carbon steel, two other types of steel often used to fabricate certain components of construction equipment are low-alloy steel and high-alloy steel. An alloy steel, besides consisting of iron and carbon, also has one or more alloying elements added—silicon, manganese, chrome, nickel, molybdenum, columbium, titanium, vanadium, or copper. T1 steel is a trade name for A514 steel, a high-alloy steel with a tensile strength of 100,000 psi, often used for certain components of construction equipment that need high strength, such as the arms supporting the bucket of a front-end loader. This A514 or T1 steel is also available in steel plate, which in the repairing of loader or excavator buckets is often welded to inside or outside bucket surfaces.
There are some components of construction equipment—for instance, gears, the drums used for reeling in cables, and cable pulleys (as on drag lines) - that are made of carbon steel. While their base may be fabricated from a mild carbon steel, typically they are overlaid with a surface deposit of hard metal-to-metal tool steel, with a Rockwell hardness range of 40-55 Rc. There is very little stainless steel used in construction equipment.
Given these different kinds of steels, please itemize more fully the major components of construction equipment and the type of steel each is made of.
Black: Generally the type of steel selected by construction equipment makers depends on what strength is needed for the particular component. The sheet steel of cabs is low-carbon steel, a mild steel.
The chassis of a low-boy trailer for carrying construction equipment is typically made of carbon steel. But a trailer designed for carrying a large, heavy dozer might be fabricated of a high-alloy steel that has been quenched and tempered to bring the tensile strength up to about 100,000 psi.
The booms and arms of backhoes and excavators, since they need considerable tensile strength, are often made of low-alloy steels that have been heat-treated to get the needed tensile strength—50,000-100,000 psi—and toughness levels. The arms supporting loader buckets and the push arms holding dozer blades are often made of these same low-alloy, heat-treated steels.
The buckets of loaders and excavators need to have both high strength and some abrasion resistance and thus are often fabricated of low-alloy or even high-alloy steels. Concerning the undercarriages of dozers and other tracked construction equipment, the sprockets, idlers, and rollers typically are made of low-alloy steel, iron, and carbon alloyed with chrome, nickel, and molybdenum (SAE 4130 or 4340). Often the surface of these components would be flame- or surface-hardened to provide metal-to-metal wear resistance. In the rebuilding of such undercarriages, workers often apply a hardfacing material that would be comparable to the original surface-hardened material, now worn off.
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What welding methods are most commonly used in the repair of construction equipment?
Black: In today’s world, most construction work is done using some type of electric arc welding. Oxy-fuel welding, in which a high-temperature flame is created by reacting acetylene, propane, or some other gaseous fuel with oxygen, is not used to any great extent in the repair of construction equipment. This is because electric arc welding is much faster than oxy-fuel welding, an efficient welder being able to deposit 15 pounds per hour of weld material with certain arc-welding methods versus the mere 3 lb./hr. with the oxy-fuel approach. Electric arc welding is much faster because the electric current is much faster at melting the weld material than the oxy-fuel flame is.
What really is electric arc welding?
Black: Arc welding is the controlled use of electric current (amperage) to melt both the base and the consumable material. The major types are stick, continuous wire with automatic or semiautomatic feed, and tungsten inert gas, not widely used in construction-equipment repair.
What are the advantages of stick arc welding?
Black: One major advantage is that the price of the equipment for stick welding–mainly, the field power source consisting of a diesel or gasoline engine coupled to a generator or an alternator - is low compared to other types of equipment. Also, this equipment is highly portable.
Another major advantage to stick welding is that it is very easy to change the weld material. The weld material is the particular alloy of which the electrode is composed; it is a consumable electrode. It is an easy matter to unclamp the present electrode and clamp in a new one made of the weld alloy needed at that moment.
Still another key advantage of stick arc welding over other methods of arc welding is that it can also be used for out-of-position welding—that is, for welding in vertical and overhead positions. This makes the stick-welding approach very suitable for doing hardfacing and other welding tasks in the field.
Clearly, the power source is the main item needed for field arc welding. Please explain size ranges, weights, prices, and so on.
Black: There is a wide range of electrical power sources available on the market for field welding. Such sources typically consist of either a diesel or a gasoline engine driving a direct-current generator or alternator with a capacity to produce an output direct current ranging from 100 to 600 amps, depending on the particular model. The smallest power supplies weigh as little as 50–60 pounds, including weight of the engine. On the other hand, the higher-amp units can weigh 1,000–2,500 pounds and must be mounted in a pickup truck or on a trailer.
The most popular size power source with many construction companies doing field arc welding is something in the 200- to 250-amp range. Such a unit would typically weigh 400–600 pounds, including engine weight.
As for the price range of field power sources, the smaller gasoline-powered units, 125 amps, would sell for about $1,500, including the engine; a 250-amp unit for $5,000–$7,000; a 300-amp unit for about $8,000; and a 400-amp unit for $12,000.
If the carbon content of the carbon steel is low—0.1-0.35%—it is referred to as a mild steel or a mild carbon steel. Most construction equipment is made out of a carbon steel with a carbon content ranging from 0.1 to 0.25%, a tensile strength of 30,000-50,000 psi, and a Rockwell hardness of 5 Rc. To compare that with something more familiar, the steel used for the skeletal structure of buildings, A36 steel, is quite similar—carbon content, below 0.25%; tensile strength, 30,000-50,000 psi.
Besides carbon steel, two other types of steel often used to fabricate certain components of construction equipment are low-alloy steel and high-alloy steel. An alloy steel, besides consisting of iron and carbon, also has one or more alloying elements added—silicon, manganese, chrome, nickel, molybdenum, columbium, titanium, vanadium, or copper. T1 steel is a trade name for A514 steel, a high-alloy steel with a tensile strength of 100,000 psi, often used for certain components of construction equipment that need high strength, such as the arms supporting the bucket of a front-end loader. This A514 or T1 steel is also available in steel plate, which in the repairing of loader or excavator buckets is often welded to inside or outside bucket surfaces.
There are some components of construction equipment—for instance, gears, the drums used for reeling in cables, and cable pulleys (as on drag lines) – that are made of carbon steel. While their base may be fabricated from a mild carbon steel, typically they are overlaid with a surface deposit of hard metal-to-metal tool steel, with a Rockwell hardness range of 40-55 Rc. There is very little stainless steel used in construction equipment.
Given these different kinds of steels, please itemize more fully the major components of construction equipment and the type of steel each is made of.
Black: Generally the type of steel selected by construction equipment makers depends on what strength is needed for the particular component. The sheet steel of cabs is low-carbon steel, a mild steel.
The chassis of a low-boy trailer for carrying construction equipment is typically made of carbon steel. But a trailer designed for carrying a large, heavy dozer might be fabricated of a high-alloy steel that has been quenched and tempered to bring the tensile strength up to about 100,000 psi.
The booms and arms of backhoes and excavators, since they need considerable tensile strength, are often made of low-alloy steels that have been heat-treated to get the needed tensile strength—50,000-100,000 psi—and toughness levels. The arms supporting loader buckets and the push arms holding dozer blades are often made of these same low-alloy, heat-treated steels.
The buckets of loaders and excavators need to have both high strength and some abrasion resistance and thus are often fabricated of low-alloy or even high-alloy steels. Concerning the undercarriages of dozers and other tracked construction equipment, the sprockets, idlers, and rollers typically are made of low-alloy steel, iron, and carbon alloyed with chrome, nickel, and molybdenum (SAE 4130 or 4340). Often the surface of these components would be flame- or surface-hardened to provide metal-to-metal wear resistance. In the rebuilding of such undercarriages, workers often apply a hardfacing material that would be comparable to the original surface-hardened material, now worn off.
Editor's note: This article first appeared in the November/December 2000 edition of Grading & Excavation Contractor.
For this primer on metallurgy and welding, the author interviewed an expert in the arc-welding field, Thomas J. Black, manager of hardfacing and high-alloy products for The Lincoln Electric Company in Cleveland, OH. Black, a metallurgical engineer, has more than 40 years’ experience in the welding field.
What are the main kinds of steel used in the fabrication of construction equipment?
Black: Most of the components of construction equipment are made of some type of carbon steel. Carbon steel is the most widely used type of steel, used for fabricating structural steel for buildings, for automobiles, for washing machines, and so on. A carbon steel consists mainly of iron with some carbon—anywhere from 0.1 to 0.5%—and some silicon and manganese. There are no other alloying elements.
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If the carbon content of the carbon steel is low—0.1-0.35%—it is referred to as a mild steel or a mild carbon steel. Most construction equipment is made out of a carbon steel with a carbon content ranging from 0.1 to 0.25%, a tensile strength of 30,000-50,000 psi, and a Rockwell hardness of 5 Rc. To compare that with something more familiar, the steel used for the skeletal structure of buildings, A36 steel, is quite similar—carbon content, below 0.25%; tensile strength, 30,000-50,000 psi.
Besides carbon steel, two other types of steel often used to fabricate certain components of construction equipment are low-alloy steel and high-alloy steel. An alloy steel, besides consisting of iron and carbon, also has one or more alloying elements added—silicon, manganese, chrome, nickel, molybdenum, columbium, titanium, vanadium, or copper. T1 steel is a trade name for A514 steel, a high-alloy steel with a tensile strength of 100,000 psi, often used for certain components of construction equipment that need high strength, such as the arms supporting the bucket of a front-end loader. This A514 or T1 steel is also available in steel plate, which in the repairing of loader or excavator buckets is often welded to inside or outside bucket surfaces.
There are some components of construction equipment—for instance, gears, the drums used for reeling in cables, and cable pulleys (as on drag lines) - that are made of carbon steel. While their base may be fabricated from a mild carbon steel, typically they are overlaid with a surface deposit of hard metal-to-metal tool steel, with a Rockwell hardness range of 40-55 Rc. There is very little stainless steel used in construction equipment.
Given these different kinds of steels, please itemize more fully the major components of construction equipment and the type of steel each is made of.
Black: Generally the type of steel selected by construction equipment makers depends on what strength is needed for the particular component. The sheet steel of cabs is low-carbon steel, a mild steel.
The chassis of a low-boy trailer for carrying construction equipment is typically made of carbon steel. But a trailer designed for carrying a large, heavy dozer might be fabricated of a high-alloy steel that has been quenched and tempered to bring the tensile strength up to about 100,000 psi.
The booms and arms of backhoes and excavators, since they need considerable tensile strength, are often made of low-alloy steels that have been heat-treated to get the needed tensile strength—50,000-100,000 psi—and toughness levels. The arms supporting loader buckets and the push arms holding dozer blades are often made of these same low-alloy, heat-treated steels.
The buckets of loaders and excavators need to have both high strength and some abrasion resistance and thus are often fabricated of low-alloy or even high-alloy steels. Concerning the undercarriages of dozers and other tracked construction equipment, the sprockets, idlers, and rollers typically are made of low-alloy steel, iron, and carbon alloyed with chrome, nickel, and molybdenum (SAE 4130 or 4340). Often the surface of these components would be flame- or surface-hardened to provide metal-to-metal wear resistance. In the rebuilding of such undercarriages, workers often apply a hardfacing material that would be comparable to the original surface-hardened material, now worn off.
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What welding methods are most commonly used in the repair of construction equipment?
Black: In today’s world, most construction work is done using some type of electric arc welding. Oxy-fuel welding, in which a high-temperature flame is created by reacting acetylene, propane, or some other gaseous fuel with oxygen, is not used to any great extent in the repair of construction equipment. This is because electric arc welding is much faster than oxy-fuel welding, an efficient welder being able to deposit 15 pounds per hour of weld material with certain arc-welding methods versus the mere 3 lb./hr. with the oxy-fuel approach. Electric arc welding is much faster because the electric current is much faster at melting the weld material than the oxy-fuel flame is.
What really is electric arc welding?
Black: Arc welding is the controlled use of electric current (amperage) to melt both the base and the consumable material. The major types are stick, continuous wire with automatic or semiautomatic feed, and tungsten inert gas, not widely used in construction-equipment repair.
What are the advantages of stick arc welding?
Black: One major advantage is that the price of the equipment for stick welding–mainly, the field power source consisting of a diesel or gasoline engine coupled to a generator or an alternator - is low compared to other types of equipment. Also, this equipment is highly portable.
Another major advantage to stick welding is that it is very easy to change the weld material. The weld material is the particular alloy of which the electrode is composed; it is a consumable electrode. It is an easy matter to unclamp the present electrode and clamp in a new one made of the weld alloy needed at that moment.
Still another key advantage of stick arc welding over other methods of arc welding is that it can also be used for out-of-position welding—that is, for welding in vertical and overhead positions. This makes the stick-welding approach very suitable for doing hardfacing and other welding tasks in the field.
Clearly, the power source is the main item needed for field arc welding. Please explain size ranges, weights, prices, and so on.
Black: There is a wide range of electrical power sources available on the market for field welding. Such sources typically consist of either a diesel or a gasoline engine driving a direct-current generator or alternator with a capacity to produce an output direct current ranging from 100 to 600 amps, depending on the particular model. The smallest power supplies weigh as little as 50–60 pounds, including weight of the engine. On the other hand, the higher-amp units can weigh 1,000–2,500 pounds and must be mounted in a pickup truck or on a trailer.
The most popular size power source with many construction companies doing field arc welding is something in the 200- to 250-amp range. Such a unit would typically weigh 400–600 pounds, including engine weight.
As for the price range of field power sources, the smaller gasoline-powered units, 125 amps, would sell for about $1,500, including the engine; a 250-amp unit for $5,000–$7,000; a 300-amp unit for about $8,000; and a 400-amp unit for $12,000.
What welding methods are most commonly used in the repair of construction equipment?
Black: In today’s world, most construction work is done using some type of electric arc welding. Oxy-fuel welding, in which a high-temperature flame is created by reacting acetylene, propane, or some other gaseous fuel with oxygen, is not used to any great extent in the repair of construction equipment. This is because electric arc welding is much faster than oxy-fuel welding, an efficient welder being able to deposit 15 pounds per hour of weld material with certain arc-welding methods versus the mere 3 lb./hr. with the oxy-fuel approach. Electric arc welding is much faster because the electric current is much faster at melting the weld material than the oxy-fuel flame is.
What really is electric arc welding?
Black: Arc welding is the controlled use of electric current (amperage) to melt both the base and the consumable material. The major types are stick, continuous wire with automatic or semiautomatic feed, and tungsten inert gas, not widely used in construction-equipment repair.
What are the advantages of stick arc welding?
Black: One major advantage is that the price of the equipment for stick welding–mainly, the field power source consisting of a diesel or gasoline engine coupled to a generator or an alternator – is low compared to other types of equipment. Also, this equipment is highly portable.
Another major advantage to stick welding is that it is very easy to change the weld material. The weld material is the particular alloy of which the electrode is composed; it is a consumable electrode. It is an easy matter to unclamp the present electrode and clamp in a new one made of the weld alloy needed at that moment.
Still another key advantage of stick arc welding over other methods of arc welding is that it can also be used for out-of-position welding—that is, for welding in vertical and overhead positions. This makes the stick-welding approach very suitable for doing hardfacing and other welding tasks in the field.
Clearly, the power source is the main item needed for field arc welding. Please explain size ranges, weights, prices, and so on.
Black: There is a wide range of electrical power sources available on the market for field welding. Such sources typically consist of either a diesel or a gasoline engine driving a direct-current generator or alternator with a capacity to produce an output direct current ranging from 100 to 600 amps, depending on the particular model. The smallest power supplies weigh as little as 50–60 pounds, including weight of the engine. On the other hand, the higher-amp units can weigh 1,000–2,500 pounds and must be mounted in a pickup truck or on a trailer.
The most popular size power source with many construction companies doing field arc welding is something in the 200- to 250-amp range. Such a unit would typically weigh 400–600 pounds, including engine weight.
As for the price range of field power sources, the smaller gasoline-powered units, 125 amps, would sell for about $1,500, including the engine; a 250-amp unit for $5,000–$7,000; a 300-amp unit for about $8,000; and a 400-amp unit for $12,000.
